Alpha-folate receptor expression in epithelial ovarian carcinoma and non-neoplastic ovarian tissue.

The goal of this study was to evaluate the expression pattern and intracellular localization of alpha-folate receptor (alpha-FR) protein in human ovarian carcinoma compared with non-neoplastic ovarian tissue.Using immunohistochemistry (IHC), alpha-FR protein expression was analyzed in specimens of 104 human ovarian carcinomas and 30 non-neoplastic ovaries.In 97% of the ovarian carcinomas, clear alpha-FR protein expression was detected (14% weak, 39% moderate, 44% strong). In the non-neoplastic ovaries, no (37%) or only weak (63%) expression was observed (p<0.0001). The tumor cells were characterized by a diffuse and homogeneous staining pattern. In tumor and non-tumor tissue, alpha-FR protein was detected predominantly in the cellular cytoplasm. In 41% of the ovarian carcinomas, cytoplasmic expression was localized towards the outer boarders of the invasive tumor cells and 30% exhibited additional nuclear alpha-FR protein expression.Compared with nonneoplastic ovaries, alpha-FR protein is overexpressed in human ovarian carcinoma tissue.